Manufacture of steel



Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE FREDERICK F.MCINTOSH, OF GLEN OSBORNE, PENNSYLVANIA, ASSIGNOR TO CRUCIBLE STEELOOMPANY OF AMERICA, A CORPORATION OF NEW JERSEY MANUFACTURE OF STEEL NoDrawing.

In an application for Letters Patent filed by me on May, 4, 1929, SerialNo. 360,613, I have described and claimed a new composition of steelcharacterized by high content of 5 sulphur, together with a content ofmolybdenum. In the manufacture of this steel I have also invented a newmethod of manufacture, which is the invention to which this applicationis directed.

In the manufacture of the steel referred to, I obtain the desired highsulphur con.- tent, together with the molybdenum content, by adding tothe refined steel while it is still in a molten condition the requiredquantity of the natural ore of molybdenum, known as molybdenite. In itspurity the chemical formula of molybdenite i's M03 and it contains about4.0% of sulphur and about 60% of molybdenum. This molybdenum sulphide isadded to the refined molten steel either in the ladle or as it is pouredinto the mold.

Heretofore it has been the general practice in the manufacture of steelcontainingmolybdenum, to add the molybdenum to the furzsnace charge orto the molten steel in the melting-furnace. The molfybdenum is usuallyadded in the form 0 a so-called calcium molybdate or a ferro molybdate.The

reason for adding the molybdenum composition to the steel in themeltlng-furnace is that it is diificult to get an even distribution ofthe molybdenum throughout the molten mass of the steel, for it is thefact that molybdenum is rather slow to alloy with the steel. In add ingmolybdenite to the molten steel in the ladle or in the ingot mold, Ihave found that I obtain a rapid alloying action of both elements of theaddition, and an even diffusion of the elements throughout the mass,with- Application filed. Kay 6, 1929. Serial No. 361,011.

is added at the same time at a very small cost.

The steel may be melted and refined in any suitable'melting and refiningfurnace, either a Bessemer converter, an open-hearth furnace, or anelectrical furnace, it being only essential that the steel shall bewithdrawn from the refining furnace and that the molybdenite shall beadded to the steel while the latter is still in molten condition.

I claim as my invention:

The method of manufacture of steel which comprises melting .and refiningthe steel, withdrawing the product from the refining furnace, and whileit is still molten adding to it a predetermined quantity of molybdenumsulphide.

In testimony whereof I have hereunto set my hand.

FREDERICK F. MCINTOSH.

40 out in any way impairing the quality of the steel. The molybdenumsulphide combines readily with the molten steel, and practically none ofeither component is lost; so that in practice it has been found thatwhen the molybdenum sulphide is added to the molten steel in this way,it will yield about 1.5 points of molybdenum to each point of sulphuradded. In this way the sulphur content of the steel is increased to therequired amount,

and the veryvaluable element'molybdenum

